Haematologica
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The North American Immune Tolerance Registry (NAITR) was initiated with the goal of determining, by questionnaire, immune tolerance (ITT) practices in hemophilia treatment centers in Canada and the United States. Sixty-eight centers (40%) responded. Of the 130 registry subjects with hemophilia A who completed ITT, 93 (72%) achieved tolerance. ⋯ The definition of tolerance was reviewed for the 9 subjects who relapsed and was defined by a normal recovery and survival in only 1/9 patients. Among the 11 hemophilia B subjects in the cohort who completed tolerance, 4 had a successful outcome. Four individuals were placed on maintenance regimens of 25-100 units FIX/kg/day and all remained tolerant.
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Immune tolerance induction (ITI) regimens with human factor VIII concentrates are rarely if ever implemented in adult patients with auto-inhibitors, in contrast to alloantibody suppression, which is used primarily in young children with congenital hemophilia. On the basis of some earlier experience with synchronization of plasma exchange therapy of various autoimmune disorders we have developed a new aggressive protocol for the treatment of patients with acquired factor VIII (FVIII) antibody. We have evaluated the outcome of 14 consecutive nonhemophilic FVIII inhibitor patients treated in a single center with our ITI protocol between 1992 and 1999, comparing them to 6 historical control patients, treated with traditional immunosuppression therapy (steroid +/- cyclophosphamide) between 1988 and 1992. ⋯ We conclude that the ITI protocol described here is highly effective for the treatment of acquired hemophilia, induces quick therapeutic responses and favorably influences the underlying autoimmune disorder. We suggest that our ITI protocol is suitable for the eradication of idiopathic and autoimmune-associated FVIII autoantibodies in patients presenting with severe bleeding.